Here is an excerpt from the QRH Procedure for a Pack Trip OFF:
IF Both PACK Lights Remain Illuminated:
Note: Both pack valves may have closed resulting in a gradual loss of
cabin pressure and an eventual CABIN ALTITUDE warning.
Monitor cabin altitude during the remainder of the flight.
IF Cabin Altitude Increases:
Descent...........................................ACCOMPLISH
Monitor cabin altitude and rate. Descend to lowest safe altitude or
10,000 feet, whichever is higher.
At level off:
Airspeed.............. 290 KNOTS MINIMUM
290 knots is the minimum airspeed required to maintain appropriate
cabin pressure differential with the outflow valve in the full open
position.
Pack valves may have failed in full open (hot) position.
Note: Flight deck and cabin temperatures may increase rapidly
below 290 knots depending on pack valve position.
Pressurization Mode Selector ...... MAN
Outflow Valve Switch ...................FULL OPEN
Right Recirculation Fan Switch .....................................................AUTO
Left Recirculation Fan Switch (If Installed)....................................OFF
IF Flight Deck And Cabin Temperatures Are Excessively Warm:
Flight Deck Door ............................OPEN
Galley or Cab / Util .........................OFF
BCD IFE / Pass Seat (If Installed) ........................................OFF
In-Flight Entertainment Systems..................................................... .OFF
Cabin Lighting ................................DIM
Cabin Window .......................CLOSED